


Potions Gone Wrong

by illgettoiteventually



Category: Merlin (TV)
Language: English
Status: In-Progress
Published: 2018-12-08
Updated: 2018-12-09
Packaged: 2019-09-14 05:10:44
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 7
Words: 7,776
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16906725
Author URL: https://archiveofourown.org/users/illgettoiteventually/pseuds/illgettoiteventually
Summary: Merlin thought that the only safe space to practice his spells was, for some reason, the roof. Cue an untimely explosion, all of Camelot gathered in the courtyard for the Kings speech, and an irritated Prince Arthur wondering why everyone suddenly can't see or hear him.





	1. Chapter 1

This, Merlin thought as he surveyed the chaos below him, is the last time I use magic ever again.

The day had started out well enough. He had woken up energized and ready to start the day, and even Arthur's moodiness at having to get up early wasn't able to put a dampener on Merlin's happiness. He'd gotten all his tasks done by noon, Gaius didn't have any more jobs for him and so Merlin had decided to get a little magical practice in.

The problem, as it usually was, was finding somewhere where he wouldn't be disturbed. Trying out spells in his own room usually led to bad smells for weeks at a time if they went wrong, so he'd decided to move outside. The gardens were off limits, the woods were ideal but the walk to secluded areas was long and he wanted to start right away.

So after a little deliberation, Merlin ended up on the roof. The day was pretty much cloudless, and the only wind was a soft breeze that barely rustled the leaves. He took out his spellbook from under his shirt and placed the bag of ingredients gently on the floor before sitting down himself. For a moment he allowed himself to enjoy the sun on his face before getting to work.

He'd wanted to try out an invisibility spell he'd come across in one of his late night perusals of the book. There were two of them, one that was said out loud but didn't last very long, and one that required a potion to be ingested, and lasted until the anti potion was consumed. Merlin had taken care to bring ingredients for both potions with him. One plant in particular had taken a long time to acquire, and he was extra careful when setting it down with the other ingredients.

As he set everything up he listened to the crowd in the courtyard below, citizens of Camelot who had come to hear a speech by King Uther. Merlin had no interest in what the King had to say, and had chosen this time to come to the roof precisely because no one would see him go up, everyone would be preoccupied with the King.

When everything had been set out to his liking, he began to mix the ingredients for the potion, taking care to double and triple check the instructions in the book. He wanted this to go perfectly. If he could get this potion to work as it was supposed to, and make a large stock of it, then his job of protecting Arthur would be a hell of a lot easier.

Distantly Merlin heard the chatter from below fade out, absolute silence reigning as Uther began to talk. Merlin noted this in the back of his mind, but refused to let his conscious thought stray to far from the potion.

What felt like an age later, he finally finished making the first potion, the one to turn him invisible. He held up the mixture, letting the sunlight filter through it. It was a deep purple, like amethyst, and Merlin took a moment to admire it before holding it to the page to check it was the same color as that in the books' diagram.

Satisfied that it was, Merlin allowed himself a smile before checking the next step: Hold the mixture above a fire until it turns blue. 

Clearing a space in front of him, Merlin held out his hand and concentrated, whispering a word under his breath. Seconds later a small, smokeless fire sprang up. A small grin settled on his face as he held the glass tube a little over the flame, and he glanced to the side, wondering what was going on down below.

Uther was still talking, Merlin noted with a slight eye roll, angling his head to hear better.  
"- and so I want to let my son, Arthur, speak to you now," He heard Uther say, followed by some applause. There was a few seconds of silence before Merlin heard Uther speak again, "You'll have to excuse me a moment,"  
Where was Arthur? Merlin thought, listening to the crowd start to talk again. Surely he was supposed to be by Uther’s side? 

Curiosity piqued, Merlin shifted slightly to try and see into the courtyard below. Heavy footsteps sounded out and Uther's voice once again rang out.

"My apologies, it appears my son did not realise he would be needed here today," Merlin heard the edge in Uther's voice, and tensed slightly, shifting again.

This time, however, he lost his balance. Letting out a quiet curse he threw himself forward in an attempt to defy gravity, forgetting the tube he held, and the fire it was above. His hand, with the tube, came crashing down, shattering the tube and spilling its contents into the fire. 

For a moment all Merlin could do was try not to scream as his hand burned, yanking it away from the flame. His pain became secondary, however, when he noticed the deep blue smoke now rising upwards. Gaping, Merlin scrambled back, pulling his jacket over his mouth and nose.

With a frantic glance to the side, where the courtyard was, Merlin rose up on his knees and aimed his non injured hand at the smoke,trying to focus enough to conjure wind to blow it away from them. The burning in his hand seemed to multiply, however, and he lost his focus as he whispered the words to summon the wind.

He watched in horror as the smoke blew towards the courtyard, instead of away. Panic increasing, Merlin rose into a crouch and moved to the edge of the roof, ducking down so he wouldn't be seen by anyone looking up. The smoke fanned out as it traveled, and the crowd soon noticed it, shouts rising to Merlin's ears as they made a run for it.

"SORCERY!" Merlin heard Uther shout as the warning bells sounded. Merlin kept his eyes on the increasingly hysterical crowd below.

And that is how he came to think, this is the last time I use magic ever again.

This was before he discovered the consequences.


	2. Perhaps I Forgot

It took Merlin a few moments to gather his wits before he launched himself backwards, snatching up all the potion ingredients and stuffing them into his bag along with the spellbook. He paused to use a healing spell on his hand before running to look for Gaius and put his things away.

The halls of the castle were full of panicked people rushing around, frantically asking each other if everything was alright. Merlin ignored them as he wove through the crowd, his thoughts preoccupied with what had happened. Surely the smoke itself was harmless? He hadn't had time to enchant the mixture…

He was so lost in thought he didn't see Gaius until he barreled into him, knocking them both to the floor.

"Merlin!" Gaius sputtered, giving him a Look. Stammering apologies, Merlin jumped up to help Gaius stand.

"Sorry," Merlin said quietly.

"What have you done?" Gaius asked, eyes roving over Merlin's face, picking out the guilt and panic.

"I was trying out a-" Merlin cut himself off and looked around, not wanting to admit to practising sorcery in a public space. Gaius seemed to read his thoughts, and the older man sighed heavily and gestured for Merlin to follow.

"I'm going to take a wild guess and assume that the smoke was your doing," Gaius murmured as he led Merlin to the workshop.

"Uh... well, it was an accident," Merlin replied, eyes darting in every direction as he tried to avoid the surely judgemental look Gaius would be sporting. Gaius let out another sigh and said nothing until they were safely behind closed doors.

As soon as Merlin turned around he was confronted with Gaius' most unimpressed look. With an audible gulp, Merlin set his bag down and cleared his throat.

"I was working on an invisibility potion," He said, deciding that if he just came out and said it it would be better in the long run. Gaius said nothing, just kept looking at him. Feeling the pressure, Merlin continued talking, "But... I got distracted by Uther's speech, and, well, dropped the mixture- sort of smashed it actually- in a fire. And the smoke came. I tried to summon some wind to blow it away but I'd also burned my hand and couldn't concentrate so it sort of went wrong,"

Gaius blinked, then rubbed his forehead, "Merlin..."

"I know, and I'm sorry," Merlin hurriedly said, "But it's okay, I hadn't enchanted the potion yet, just mixed the ingredients together, so no one should be feeling anything, really,"

"You're sure of this?" Gaius asked, squinting slightly.

"Well you were down there weren't you? How do you feel?" Merlin questioned, slightly nervous for the answer.

"Same as always," Gaius admitted, then paused, "I suppose you're right- though we should keep watch for anything out of the ordinary,"

"Right," Merlin nodded, "Where are you going?" He asked, for Gaius was gathering up some equipment.

"Uther has asked me to examine him. He wants to know if the smoke has had any effects," Gaius explained, giving Merlin another Look.

With a slight wince, Merlin picked up his bag and headed to his room, hiding everything under the loose floorboard. He'd just stood up again when a familiar voice reached his ears.

"MERLIN!"

With a roll of his eyes Merlin turned and left his room, coming down the steps as Arthur threw open the door to the workshop.

"Yes?" Merlin asked, wondering why Arthur looked so mad. He noted the slight irritation that rippled in Arthur's eyes, and hid his grin.

"So," Arthur stated, crossing his arms over his chest and staring at Merlin, obviously waiting for something.

"So...?" Merlin repeated after a few moments, when it became clear Arthur wasn't going to elaborate.

"Would you like to tell me why, _Mer_ lin, I was not informed that my father's speech had been moved to today?" Arthur asked, voice deceptively calm. Merlin could see the slight twitch of Arthurs eyelid, and got ready to duck.

"Well, ahem, I..." Merlin had no answer. He was sure he had told Arthur about the change.

"Well?" Arthur prompted, a lovely smile on his face. Merlin wasn't fooled, he could see Arthur glancing at one of Gaius' notebooks.

"Well," Merlin said again, "Well. Perhaps I forgot?"

"Perhaps... you forgot?" Arthur tilted his head, and Merlin saw his hand twitch toward the notebook, "Perhaps you _forgot_?"

"These things happen," Merlin said before he could stop himself. He saw it in slow motion. Arthur lunging for the notebook, his overhead swing, his livid face…

Merlin ducked just in time, and the book whipped over his head and struck the wall with a thud.  
"That was rude," Merlin huffed, crossing his arms as he looked at Arthur. He realised too late that this was probably the wrong thing to say, and moved just before Arthur did.

"GET BACK HERE!" Arthur screeched behind him as Merlin took off, dodging round the prince and flinging the door open. He sprinted into the hallway, Arthur on his heels, and ran for his life.

Merlin decided he'd be safer around other people, and so headed in the direction where he last saw crowds. He nearly lost his footing as he took a sharp turn, grinning when he heard a thud and Arthur's voice letting out a curse.

He could hear a few voices talking now, and poured on the speed, skidding into a larger hallway and, for the second time that day, knocking someone over.

"Well, Merlin, that's one way to say hello," Gwaine's familiar voice had Merlin sitting up twice as fast.

"Help!" Merlin gasped.

"What's wrong?" Leon asked, offering Merlin his hand to help him up.

"Oh that's fine, leave me down here," Gwaine muttered, "No need to help Gwaine now is there?"

"Arthur," Merlin managed to get out, "He's really mad-"

"MERLIN!"

"Help!" Merlin squeaked, ducking behind Percival's considerably larger frame.

"What's wrong with him?" Gwaine whispered loudly, giving Merlin a weird look.

"I can see you, Merlin," Arthur said, finally catching up, "And honestly, that's pretty pathetic,"

"It's not," Merlin scowled, sticking his head out from behind Percival. He located Arthur immediately.

"Not what?" Leon asked, face a picture of confusion.

"What are you looking at?" Percival asked, giving Merlin a worried look.

Arthur began stalking towards Merlin, ignoring the other knights, "I think I'll put you in the stocks,"

"That's not fair," Merlin objected, taking a step back for each Arthur took forward, "I thought I told you,"

"Merlin what are you talking about?" Gwaine spoke up again after exchanging a look with the other two.

"He missed the speech earlier and he's blaming me," Merlin said, still watching Arthur.

"Who?" Leon asked, "What are you pointing at?"

"Arthur," Merlin said, giving the knights an odd look.

"Really, Leon, I'm right here," Arthur sighed, turning to face the knights. Merlin took the opportunity to sprint past him and use Gwaine as his next shield. Arthur narrowed his eyes at him.

"Merlin you're starting to freak me out," Gwaine frowned and turned to face him, putting his hands on Merlins shoulders, "Have you been drinking?"

"No," Merlin frowned, "Why?"

"You're running away from nothing, holding conversations with thin air and acting like we're the ones who've lost it," Percival supplied.

"Thin air?" Arthur scowled, "Excuse me?"

None of the knights paid him any attention, their focus entirely on Merlin.

"Should I get Gaius?" Leon asked, placing a hand to Merlins forehead.

"Hello?" Arthur said, raising his voice.

"You should stop ignoring him," Merlin advised, "Before he gets mad at you guys too,"

The three knights shared worried looks, "Merlin," Gwaine said gently, "You should get some rest,"

"That's it," Arthur threw up his hands and marched forward, pushing Gwaine and Leon out of the way and grabbing Merlins arm, "We're leaving,"

"What the f-" Gwaine gaped, "What the hell was that?"

"This isn't funny," Arthur spun around, glaring at him.

"I'll take Merlin to Gaius," Percival said, glancing around, "Maybe he took in some of that weird smoke,"

" _We_ aren't hallucinating though," Leon said, hand drifting to his sword hilt.

"What is going on?" Arthur spun and looked at Merlin, "It's like I'm invisible or something,"

It was then that Merlin realised what might be happening.

"Oh," Was all he said.


	3. Isn't The Tavern More Your Speed?

"Come on, Merlin," Percival said gently, like he was a wild animal, "I'll take you to see Gaius, okay?"

  
"No!" Merlin said, louder than he meant to. His suspicions about Arthur, and why the knights weren't acknowledging him, were becoming clearer by the minute. He had to make sure he was right, "No," He repeated, calmer this time, "I... I just need a little more sleep," 

  
"Arthur working you too hard?" Leon asked sympathetically, while Gwaine looked at him doubtfully.

  
"Work  _ you _ too hard?" Arthur said, incredulous, his eyebrows rising so high on his forehead they very nearly reached his hairline.

  
"Yes," Merlin sighed dramatically, "I need an afternoon to myself, to recover. Lack of sleep has made me a little..." He waved his hands about, unable to find the words. The knights nodded in understanding before moving off, Gwaine glancing over his shoulder a few times.

  
As soon as they rounded the corner, Arthur grabbed Merlins arm and yanked him into the nearest room, shutting the door and staring at Merlin.

  
"What was that about?" Arthur demanded, "Why were they pretending they couldn't see me? Is this some joke you're all playing?"

  
"If it was a joke I'd like to think I'd be in on it," Merlin muttered, then looked at Arthur, "I think they really can't see you, or hear you,"

  
Arthur stared at him for a moment, then snorted, pushing him out of the way he threw open the door and strode out into the hallway beyond. Merlin followed with a quiet sigh, noticing two serving girls were walking towards them. Arthur stopped in the centre of the hall and faced the girls.

  
"Excuse me," Arthur said, a charming smile on his face. The girls paid him no attention, barely sparing him a glance as they swept passed, nodding and smiling to Merlin as they went. Arthur frowned and followed after them.

  
"Hello?" He said, walking next to them and waving a hand in front of their faces. He glanced back at Merlin, unnerved. Without warning, Arthur jumped in front of the girls, screaming. Merlin choked on laughter as they continued walking, and Arthur's face fell.

  
"I don't get it," Arthur said, walking back to Merlin, "They didn't even look at me,"

  
"I noticed," Merlin grinned.

  
"This isn't funny, Merlin," Arthur glared, "If people really can't see or hear me, then- wait,"

  
"What?"

  
"Why can  _ you _ see me and they can't?" Arthur looked at him, suspicion lacing his voice.

  
"I don't know," Merlin frowned, mind racing to figure out an explanation, deciding that a little bit of truth was in order, "Maybe... maybe it has something to do with that smoke the others mentioned earlier?"

  
"Smoke?" Arthur repeated.

  
"Mhm, earlier today, during the speech, apparently some kind of smoke blew over the crowds. Perhaps everyone who inhaled it, even a little, is unable to see or hear you," Merlin said.

  
"And you didn't breathe any of this smoke in... why?" Arthur asked.

  
"I was... busy," Merlin replied.

  
"Getting some rest after all the hard work you do for me," Arthur nodded, a sarcastic smile on his face, "Of course,"

  
"And yet if I hadn't been getting that rest you wouldn't have anyone around to help you," Merlin replied smugly.

  
Muttering under his breath, Arthur moved towards the window, leaning against the wall and looking out, "So what do we do?" He asked.

  
Merlin had no idea. He needed to talk to Gaius, and check the spell book to see if it had any solutions. Maybe if he made the antidote and recreated what happened on the rooftop?

  
"Merlin," The sound of his name jerked him out of his thoughts, and he looked at Arthur.

  
"Yes?"

  
"What do we do?" Arthur asked again, turning to look at him.

  
"Well," Merlin began, wondering how to spin it, "This is obviously sorcery-"

  
"So we can't go to my father," Arthur said, tapping his foot.

  
"We can't?" Merlin asked, thrown off. He had expected Arthur would need convincing to  _ not _ tell Uther, yet here he was.

  
"You’re the only one who can see me, Merlin," Arthur said slowly, as if explaining this to a child, "My father will probably take that as a sign you're a sorcerer. We can figure this out ourselves,"

  
"Okay, I guess," Merlin nodded, "Well I'm no sorcerer but I suppose we would need to find out the kind of spell used, and that would lead us to the spell to reverse it,"

  
Arthur nodded, a smile seeming to tug at his lips before his expression neutralised, "But we would need a sorcerer to perform the reversal spell..."

  
"We cross that bridge when we come to it," Merlin said, already thinking of ways to solve that particular problem, "What we need to do now is find what spell was used,"

  
"So we talk to those who were in the courtyard, find out what they saw," Arthur said, standing up and almost buzzing with energy, "And work from there,"

  
"Right," Merlin nodded, "We should split up,"

  
Arthur had been walking towards the door when Merlin spoke. He paused and gave Merlin an exasperated look, "What? Why?"

  
"Well, we can talk to more people that way," Merlin said.

  
"Aren't you forgetting something?" Arthur asked, rolling his eyes.

  
"I don't think so," Merlin replied.

  
"I. Am.  _ Invisible _ ," Arthur said, leaning forward and enunciating each word, "People. Can't. See. Or. Hear. Me."

  
"Ah. Yes," Merlin smiled nervously, "You can go to the tavern and eavesdrop," 

  
"Isn't the tavern more your speed?" Arthur asked sweetly.

  
Merlin decided to act as if Arthur hadn't spoken, "I'll speak to Gaius and find out if he knows anything. See what you can pick up from listening to people's conversations,"

  
And with that, Merlin opened the door and left, heading for the workshop and hoping Gaius was back. 

  
He had a lot of work to do. 


	4. That's Why We Love Him

"I'm sorry, what?" Gaius openly gaped at Merlin, who had just finished telling him that actually, the potion had affected people.

  
"Arthur is invisible to anyone who inhaled that smoke," Merlin said, "They can't see or hear him,"

  
"You said you hadn't yet enchanted the mixture when you dropped it!" Gaius hissed, looking behind him to check the door was shut, "Get the book,"

  
Merlin nodded and hurried into his room, pulling up the floorboard and extracting the book before practically sprinting back to Gaius. He flipped through the pages, coming to a stop at the invisibility potion, "Here," He said, handing the book to Gaius.

  
The older man took the book and cleared a space on the table for it, pulling out his spectacles and leaning  over the page, brows furrowed as he read.

  
"I presume you were up to ' **Hold the mixture above a fire until it turns blue**.' when you fell," Gaius said, looking up at Merlin for conformation, then back at the book at Merlin's nod, "I don't quite understand how the smoke affected everyone like this if you hadn't used magic on it. Potions need to be infused with magic to work," 

  
Merlin nodded, crouching next to Gaius to look at the book, and scanning the page to look for any clues as to what to do in case it went wrong. Nothing. Nothing at all.

  
"Patience," Gaius said, sensing his frustration, "We'll find something. Why don't you go down to the library, to that room you found the goblin in? There may be something there,"

  
"I forgot about that," Merlin straightened up immediately, running for the door.

  
"Be careful!" Gaius' shout chased him into the hallway. Merlin slowed only when he was right outside the library, holding onto the wall to catch his breath.

  
"Merlin," 

  
He whirled around to see Gwen smiling warmly at him.

  
"Gwen, what are you doing here?" Merlin asked, trying and failing to hide his breathlessness.

  
"I'm on my way to the kitchens," Gwen said, looking him over, "Are you alright?"

  
"Of course. Why wouldn't I be? Are  _ you _ alright?" Merlin replied, smiling widely.

  
"I'm... fine," She smiled again, a little uncertain this time, "I'll just... be going,"

  
"Bye!" Merlin called after her, waving when she looked back. When she was out of sight he straightened his clothes and opened the library door, quietly stepping in and shutting it behind him.

  
The moment he turned he met the gaze of the librarian, his disapproving eyes boring into Merlins own. Merlin tried for a bright smile, but the librarian just let out a huff and went back to his papers. Pressing his lips together, Merlin quickly walked passed the desk, speeding down the corridor. He turned into a smaller room, lined with bookshelves, and headed for the one on the right.

  
Finding the shelf he pushed down and kept hold of it as the entire case turned. The temperature of the air shifted, turning colder as the case stopped and Merlin took a few steps into the room. Using his magic to summon a small flame in his hand, Merlin looked around. It had barely changed since the last time he had seen it. 

  
Holding his hand higher and letting the golden light spread through the dark space, Merlin moved towards the nearest books and grabbed the stack before setting them down on the floor. He spent the next minute gathering all the books he could see before sitting down next to the various stacks and surveying them with a sigh.

  
He should have gone to the tavern instead.

 

-

  
Meanwhile, Arthur was having the time of his life. Usually he couldn't go anywhere without people staring and pointing at him. Now he could go anywhere, do anything, and not be constantly watched and judged. He was already on his way to the kitchens, and whilst he told himself he wanted to hear what the cooks were saying about the smoke earlier, he really just wanted food.

  
Keeping one ear on the conversation between the cooks, Arthur headed for the table near the back of the kitchen that held a large array of pastries and cakes.

  
"Never seen such chaos!" One of the women was saying, "Everyone running round, half out of their minds wondering what that smoke was going to do to 'em,"

  
"Such a strange colour too," Another piped up, "Never seen smoke quite like it,"

  
"Some people said it came from the roof," Said a man, kneading dough, "A sorcerer trying to curse Camelot,"

  
"With smoke?" A younger girl asked doubtfully, looking unimpressed, "I don't think so,"

  
"And what would you know about it?"

  
"Practically everyone in Camelot took some of that smoke in," The girl said, "Do you feel cursed? Sick? Like you're about to drop dead?"

  
Arthur had now reached his goal and stepped closer to the wall, running an eye over all the available food. With a grin he picked up a pastry from the closest plate and began eating.

  
"Of course not," The man answered, "I'm working aren't I?"

  
"Maybe it takes time to have an effect?" Another woman said, looking down at herself. The younger girl snorted and turned away, shaking her head.

  
Deciding he'd heard enough from here, Arthur scooped up some more pastries and made his way out of the kitchens. He was in the hallway when he heard another set of voices.

  
"- Just seemed a little strange, that's all," Gwen was saying, "He was outside the library,"

  
"Well Merlin's always been a little odd," He heard Morgana reply, "But that's why we love him,"

  
"Yes but this time I think something might be wrong," Gwen said, "Leon said they ran into him earlier and he was hallucinating,"

  
Arthur stepped into a small alcove as the two women passed, forgetting he was actually invisible. When he realised what he'd done he flushed, and was momentarily glad Merlin wasn't here to see it.

  
"Hallucinating?" Morgana asked, sounding more concerned, "Maybe Arthur knows what's wrong?"

  
"No ones seen Arthur for a while," Gwen said, "Since the speech. Uther's been wanting to speak to him but he's nowhere to be found. Leon said Merlin was actually hallucinating about Arthur,"

  
Their voices faded away, and Arthur stepped out into the hall, food forgotten. If he and Merlin couldn't lift the spell soon, his father would assume he was kidnapped, and claim the sorcery was a distraction. He needed to find the spell used, before everything went to hell. 


	5. The Arthur Aspect

It was late in the night when Merlin finally returned to Gaius, weary and dejected after hours of searching and turning up no solutions. He trudged into the workshop, eyes downcast, and sighed heavily.

"Nothing," He said to the older man, "I read every book in that place and found nothing at all. The only time invisibility was mentioned was as an offhand comment. I want to die. Why does this always happen to me?" He threw himself onto a bench and sighed heavily, dropping his head onto his arms.

After a moment of silence he looked up at Gaius, wondering what the cause of his silence was. The older man was flipping through a book, demeanor unchanged by Merlin's arrival.

"Gaius?" Merlin prompted, "Did you hear me?"

"Crystal clear, Merlin," Gaius replied, turning the page.

"And?" Merlin said. "And I do believe I've figured out why the smoke affected people the way it did," Gaius said with a small smile, setting down the book and leaning his elbows on the table, "But first, what were you thinking about before you fell over?"

"What?" Merlin asked, baffled.

"What was on your mind when the tube smashed?" Gaius asked again.

Merlin thought the question strange, but cast his mind back at Gaius' expectant look, "Well... I was listening to Uther announce Arthur was coming to speak and then... he said Arthur wasn't there, so I was wondering what Arthur was doing that caused him to miss it,"

Gaius nodded, like he expected Merlin's answer to be something like that, "And you used magic to try and blow the smoke away, correct?"

"There wasn't an alternative," Merlin replied, "Why all the questions?"

"Just making sure things happened as I thought they did," Gaius said, "Or I'd be wrong,"

"You know why it happened?" Merlin asked, sitting up straight.

"A mere theory," Gaius said, "The potion was made to render whoever consumed it invisible. You had completed the mixture when you were heating it, and the only thing left to do would have been for you to infuse it with magic. Now you infused the potion - which was in smoke form - with magic when you attempted to use air to blow it away from the crowds, which is why it actually affected people,"

"And the Arthur aspect?" Merlin asked.

"Your mind was on him just before you dropped the potion," Gaius said, "And he was likely on your mind, albeit pushed to the side, when you used magic. That's why people can't see or hear him. Your potion was a success, just not in the way you intended it to be,"

"And there's a way to reverse it?" Merlin asked, excitement sparking adrenaline.

"I believe that if you make the anti potion, drop it in another fire and blow the smoke over Camelot, then it should reverse the effects of the other," Gaius said with a satisfied smile.

"That's so simple," Merlin marveled, "I should of realised that was possible,"

"Fetch the ingredients and we can make the potion now," Gaius said, "Everything will be put to rights by morning,"

Now that he had some hope Merlin moved with a spring in his step. He took out the bag from under the floorboard and brought it back to Gaius. Moving quickly but carefully Merlin placed everything on the table, standing aside as Gaius checked each ingredient against the list in the book.

"We're missing something," Gaius said, checking again, "You had everything for the anti potion didn't you?"

Merlin nodded and came to see for himself, thinking it was just one of the more common plants that could be easily procured with a quick trip into the woods. It took him a few moments to realise what, exactly, was missing.

Merlin had, in his short life, become accustomed to misfortune.

That didn't stop him from wanting to curl up on the floor and cry when he found out that the one missing ingredient was the very plant he had taken such care with just that morning.

The very plant that had taken him a little over a month to acquire.

He really hated life.

-

Arthur wasn't any luckier than Merlin. After leaving the kitchens he headed out into the lower town, listening to dozens of conversations in the market and the blacksmiths and the tavern. The tavern he stayed in the longest, since people were coming and going and the ale intake made them loose lipped.

He had heard dozens of conspiracy theories and more rants than he cared to, and not one person seemed to actually know what they were talking about. All speculation, no facts.

Arthur couldn't fault them, though. The ban on magic meant that knowledge of the old religion was scarce, and the people were likely afraid of admitting they knew more than they let on. It was nearing midnight when Arthur finally called it a day and headed back home, hoping Merlin had had more luck than him. The novelty of his invisibility was wearing off.

He returned to his room to wait for Merlin, knowing his manservant would come and check in on him soon enough. An hour or so later, when Arthur was dozing off on his bed, Merlin walked in. The inclination to throw something at him for waking him up was strong, but the feeling was put aside when he saw Merlin's face.

“What is it?” Arthur asked, dread pooling in his stomach. Merlin looked exhausted, his eyes were downcast, his shoulders were drooping and his feet were dragging on the floor. Merlin heaved a sigh and threw himself into a chair, dropping his head into his hands.

Arthur waited all of ten seconds before speaking again, “Merlin?”

Merlin looked up, running a hand through his hair before using it to prop up his head, “We have good news and bad news. Me and Gaius know how to reverse the spell, and we have most of the ingredients,”

“But?” Arthur said when Merlin paused, knowing that something was wrong.

“The main ingredient is a rare plant that would be extremely difficult to get. Which is of course the only one we don't have,” Merlin told him, looking forlorn, “If we could somehow get that plant we’d just need a sorcerer to make the potion. We'd just have to throw it in a fire and get them to blow the smoke over Camelot, and you'd be visible again,”

“So we need a sorcerer and a rare plant,” Arthur said. When he put it like that it sounded remarkably simple. “Right. And do we have any clue where to find this plant?”

“Yes,” Merlin said.

“And?” Arthur prompted, wondering why he looked so devastated.

“They grow underwater,” Merlin said, “In a cave by the sea,”

“That's… not too bad,” Arthur said. He was was a strong swimmer, and could hold his breath for quite a long time. “

Yeah,” Merlin said, “Except… only one grows. One every year,”

“And… it's been picked?” Arthur asked, already knowing the answer. Merlin said it anyway.

“Yeah. Yeah it has,”


	6. Arthur Said Something Intelligent For Once

They sat together in silence for a long time after that, both of their minds racing, trying to find a solution to the problem.

"Surely it's not the only plant?" Arthur said, his voice shattering the tense silence.

"If it wasn't then I would know about it," Merlin replied, finally looking up.

"How does the plant grow? Surely it needs a seed right? If the plant has already been picked perhaps there's a seed left behind?"

"We'd still need to wait a year, Arthur," Merlin said.

"No, we'd need a sorcerer," Arthur said, grinning, "We get the seed or whatever it grows from, we take it to a sorcerer and get them to use magic to grow it,"

Merlin blinked at him, tired eyes blank for a moment. The moment he properly understood what Arthur was saying his whole posture changed. He literally leapt out of his seat, his blue eyes shining and a manic grin on his face.

"Wait here," He ordered Arthur before running out of the room. Arthur had a moment of offense before he was up and chasing after Merlin wondering what had gotten him so excited.

Merlin sprinted back to Gaius' workshop, and threw open the door with an excited shout of "Gaius!". Arthur managed to skid to a stop before he could get hit with the doors rebound. It hit the frame and swung open again, but Arthur caught the handle before it could reveal him to the room - more importantly to Merlin.

-

"What is it?" Gaius asked clutching at his chest.

"Sorry," Merlin said, guilt momentarily freezing him, "It's just- Arthur said something intelligent for once and essentially handed us the solution,"

"Well what is it?" Gaius asked. Merlin didn't answer for a moment, his focus entirely on the books lined on the shelves, searching for one in particular. When he had first decided to try out the invisibility potion he hadn't been too sure on what all the plants listed were, so he'd used a few of Gaius' books to find out. One of them contained the information on the rare plant they were missing, and Merlin knew it would reveal its growing process.

Finally he found it, tucked away at the end of the shelf, wedged between the wall and a large leather bound book. He managed to wriggle it out and started speaking as he flipped through it, "Arthur said there has to be a way for the plant to grow, a seed. He thought if we could get it we could use a sorcerer to speed up the growth,"

"That's quite smart," Gaius said, and a quick look up revealed his expression was one of approval, "But there's a question of if there even is a seed. I always thought since there was only ever one growing, once a year that it was a magical process,"

"As did I," Merlin said, smiling as he scanned the page, "Luckily for us, that's not the case. It says here that the plant is natural in origins, and the cave where it grows is the only place it does because of specific minerals in the water. Each year the plant grows, and a seed develops in the stem. If the plant isn't picked then it dissolves, leaving the seed behind to grow again. If it's picked the stem breaks off just before the section the seed is contained in, leaving it in the soil to grow over the next year,"

"So we have some hope," Gaius breathed out a sigh of relief, sinking in to a chair, "For a time I truly thought..."

Merlin nodded, though Gaius wasn't looking at him. The relief he himself felt was almost enough to bring him to his knees. He took a deep breath and placed the book on the table, bracing his hands on the rough wood for a moment before stepping back.

"I'll go pack a bag," He said, "The cave's a few days journey. I'll go and use my magic to grow it in the water, I don't want to risk it elsewhere. I'll be back as soon as possible, keep Uther distracted and see if you can find some way to tell Arthur I'm sick. He knows you're aware he's invisible so maybe just go to his chambers and say it,"

Merlin was moving for his room before Gaius replied. The plant had taken a month for him to get before because the book had said it was only fully grown at the peak of summer. He'd had to wait until that time came before going to pick it. Now, though, he could leave immediately without worrying about perfect time frame to go and retrieve it.

"I can tell Arthur when I come back that I found a sorcerer on the way to get the plant," Merlin said, coming out of his room, "That they saved me from bandits or whatever and agreed to help. The spell will be reversed when I come back anyway, he'll probably be too happy to question it too much,"

"You can't mean to leave now," Gaius said, frowning at him. 

"I-"

"You need to rest, Merlin," Gaius said sternly, "You've had a long day. If you injure yourself you wont be able to help anyone,"

"But-"

"You can leave at dawn," Gaius cut him off and crossed his arms, "Or not at all,"

"... Fine," Merlin said, "You're right."

Gaius nodded and watched as Merlin turned and went back to his room. He waited until the door shut before turning to sit at his bench, deciding to catch up on his work. And if he was also keeping an eye out for Merlin trying to sneak by, well, who was going to know?

-

Outside the door Arthur stood frozen for a few seconds, before sharply turning around and marching back to his rooms.

He didn't sleep for the rest of that night.

 


	7. Just My Luck

 

 

Despite his initial protests, when Merlin lay on his bed he fell asleep instantly, the hectic day he'd had lending him a bone deep exhaustion. Gaius woke him up just as the first rays of sunlight touched the world, the cold in Merlin's room causing him to shiver slightly as he went through the motions of getting dressed. Once ready he picked up his bag and left his room, gently closing the door behind him. He accepted the bread and cheese Gaius handed him with a grateful smile, though the anxiety knotting his stomach left him devoid of hunger. He wrapped the small meal in a cloth and put it in his pocket, sure that once he was on his way his appetite would return.

"Be careful," Gaius told him sternly, "I know you are eager to fix the problem, but rushing will lead to mistakes, dangerous ones,"

"I know," Merlin attempted a smile, "I'll look after myself,"

Gaius nodded and handed him a smaller bag, and a quick look inside revealed food for the next few days, "I assume you'll want to take the fast route," He said, "Which includes not stopping at villages,"

Mouth twitching into a small smile Merlin packed it away, giving Gaius a grateful nod before heading for the door. Sticking close to the walls as he crept through the dark castle, Merlin remained on high alert, freezing at the sounds of echoing footsteps or faint voices drifting in from halls away. He finally made it to the stables, slipping inside through a small gap and turning to close the door and make sure it didn't slam.

"Merlin!"

Though he later denied it, Merlin let out a decidedly high pitched scream.

"Seriously?" Arthur snorted as he strode out of the darkness, "I'll pretend I didn't hear that so you can retain _some_ sense of dignity,"

"What are you doing here?" Merlin hissed, and was grateful for the darkness hiding the redness of his cheeks.

Arthur gave a casual shrug and waved his hand around, "When you ran out yesterday I figured you had a solution so I took it upon my self to get everything ready for our subsequent journey to fix the invisibility issue," He grinned, then fixed Merlin with an intense stare, "You did find a solution, didn't you? That's why you're here?"

"I- Yes," Merlin replied, biting his lip, "But I think it's best for me to go alone,"

"Oh really?" Arthur raised a brow, "Please elaborate,"

"That's, well, you know, I think it'll be easier to go alone," Merlin eventually said. Arthur stared at him, clearly waiting for more.

"That's it?" Arthur said incredulously, "That's your reasoning?"

"Well, yes," Merlin said.

Arthur rolled his eyes and gestured for Merlin to follow him, "Well while that's a stellar argument I'm afraid I'm going to have to insist on coming along. Who else is going to protect you from all the nasty things in the woods? Also, it'll be boring to stay in the castle when no one can acknowledge me, so, we go together,"

"But-" Merlin started, but Arthur had walked away. With a sigh Merlin followed after him, and found him with two saddled horses.

"Let's go," Arthur said without turning, taking the reins of the black horse and leading it past Merlin.

"Just my luck he'd be here," Merlin muttered as he took up the reins of the second horse which had a dark brown coat, and led it outside.

"Lead the way," Arthur told him, before getting on his horse and waiting for Merlin to do the same. With another sigh Merlin did so, wondering how he always managed to work himself into more and more trouble.

-

Arthur rode behind Merlin, his own thoughts preoccupying him. He kept thinking about the conversation between Gaius and Merlin last night. Merlin intending to come and do this alone, and thinking he, Arthur, wouldn't care what happened, or question him too deeply, as long as his invisibility was reversed. It made him feel a little sick, a little sad and very, very guilty. It was his own behaviour that led Merlin to the conclusion of Arthur's indifference to him, the façade he wore so Merlin wouldn't know that Arthur knew about his magic.

Ever since Merlin had arrived in Camelot strange things had happened wherever he was. It took Arthur all of a few weeks to realise Merlin had magic, and all of a few seconds to decide to do whatever it took to protect Merlin and make sure he wasn't found out by the King, who wouldn't think twice about sentencing Merlin- and had already done so on several occasions.

Arthur had waited for Merlin to tell him, of his own accord, that he had magic. That he'd eventually trust Arthur enough to reveal his secret, but that hadn't happened yet, and judging from what he'd heard last night, it seemed like Merlin never would. Letting out a breath Arthur shook his head and glanced around at the trees on either side of the narrow path they were following. They were packed closely together, and a canopy of leaves filtered any overhead sunlight. Arthur guessed it was nearing mid morning.

  
He looked ahead to Merlin, who hadn't relaxed since they'd started out in the early morning. Arthur knew Merlin was likely wondering how to perform the spells necessary with him there, and the guilt rose again at making this more difficult for Merlin, but he couldn't let his friend go alone. He knew Merlin could take care of himself, but Arthur also knew waiting for Merlin back in Camelot would of driven him mad. Besides, Merlin needed someone to watch his back too, knowing him he'd probably trip over and fall off the cliff or something equally as ridiculous.

He considered telling Merlin he knew about his magic, to take at least one burden off his friends shoulders, but he didn't know how Merlin would react. Would he be glad Arthur knew about it? Happy he didn't have to hide such a huge part of him from Arthur anymore? Or maybe he would be angry, or disappointed, sad, even, that Arthur had let him go all this time believing he was ignorant of Merlin's magic?

"What's wrong?" Merlin's voice jerked Arthur out of his thoughts, and he looked up at Merlin who had swivelled around in his saddle to look at him.

"Nothing," He said after a moment, then yawned, "Just tired,"

"There's a small clearing coming up," Merlin said, "We can stop for a while, have something to eat,"

"Alright," Arthur agreed.

"Great. I'm gonna turn back now, because my spine is hurting," Merlin said, eliciting an eye roll from Arthur.

He stared at Merlin's back for a few moments, thinking. Then he made his decision.

 

**Author's Note:**

> Thanks for reading, let me know what you think!


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